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  1. #1
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    Default Some kind of relief valve?

    This is on the hot line at the water heater. The copper pipe at the top goes outside and is open, as if this is some kind of relief valve. Never seen this before. Water heater is typical with the usual TPR valve.

    wh device.jpg

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    "There is no exception to the rule that every rule has an exception." -James Thurber, writer and cartoonist (1894-1961)
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  2. #2
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    Default Re: Some kind of relief valve?


  3. #3
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    Default Re: Some kind of relief valve?

    Quote Originally Posted by John Arnold View Post
    This is on the hot line at the water heater. The copper pipe at the top goes outside and is open, as if this is some kind of relief valve. Never seen this before. Water heater is typical with the usual TPR valve.

    wh device.jpg
    I have not seen one like that, but may be a pressure relief valve for thermal expansion. Could also be a vacuum break valve, but it does not look like the ones I have seen.


  4. #4
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    Daniel Island, SC.
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    Default Re: Some kind of relief valve?

    Quote Originally Posted by Mark Reinmiller View Post
    I have not seen one like that, but may be a pressure relief valve for thermal expansion. Could also be a vacuum break valve, but it does not look like the ones I have seen.
    That looks dangerous!


  5. #5
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    Default Re: Some kind of relief valve?

    As Dom said, it's likely a pressure relief valve used for thermal expansion ...

    Quote Originally Posted by Dom D'Agostino View Post
    However ... keep in mind that the maximum allowed pressure for the system is 85 psi - that pressure relief valve needs to be set no higher than 85 psi (most I find are set to 100 psi).

    The T&P relief valve is set to 150 psi - that is allowed because that is a safety relief device for the tank, not a pressure limiting device for the system.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  6. #6
    Jack Foster's Avatar
    Jack Foster Guest

    Default Re: Some kind of relief valve?

    Looks like a jerry-rigged pressure relief with a vacuum breaker to drain the line, except that the actual relief mechanism seems to be missing (plugged with something white?).

    I can't quite read the information stamped into the side of the relief valve(?). You might be able to find more information from the manufacturer of that portion.

    Is that a grub screw on the bottom of the rv portion?
    wh device marked up.JPG


  7. #7
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    Default Re: Some kind of relief valve?

    I don't even know what a grub screw is.

    Did I mention that the homeowner is an engineer?

    "There is no exception to the rule that every rule has an exception." -James Thurber, writer and cartoonist (1894-1961)
    www.ArnoldHomeInspections.com

  8. #8
    Jack Foster's Avatar
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    Default Re: Some kind of relief valve?

    Quote Originally Posted by John Arnold View Post
    I don't even know what a grub screw is.
    A grub screw is a small screw that penetrates the side of a female pipe or fitting that bites into the male pipe and locks the fitting in place. They are commonly seen on the screw-on hose-bib anti-siphon devices. In that case the screw is turned in until the head breaks off. This prevents the removal of the device without damaging the male threads (in theory).

    If the item in the photo is a grub screw, it would certainly indicate that this likely is a field assembled contraption, as it appears to be.

    As for this thing being a temperature and/or pressure relief, it doesn't appear that there is enough room for the "tail" of the typical relief valve. It looks like someone just used a valve body to rig up whatever this thing is supposed to be.


  9. #9
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    Default Re: Some kind of relief valve?

    Quote Originally Posted by Jack Foster View Post
    If the item in the photo is a grub screw, it would certainly indicate that this likely is a field assembled contraption, as it appears to be.

    As for this thing being a temperature and/or pressure relief, it doesn't appear that there is enough room for the "tail" of the typical relief valve. It looks like someone just used a valve body to rig up whatever this thing is supposed to be.
    It's a pressure relief valve, not a temperature relief valve, no "tail" is needed for pressure relief valves.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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